let str:unknown=1
str="this is typescript 3 msg!"
// let len:number=(<string>str).length
let len:number=(str as string).length
console.log('字符串str的长度是',len);
console.log('**********************');

type newStrType=string|string[]

let a:newStrType="hello Giles"
// a=['Giles','Monica']
console.log(a.length);
console.log('*************************');

const fun23=(x:number,y:number,z:number):number=>x+y+z

type FunType=(x:number,y:number,z:number)=>number

const fun33:FunType=(x,y,z)=>x+y+z






